How to display custom tags?

Ok, so now I've created my first skin, which does some things better already for me than existing skins. But now come the more detailed refinements. I have a couple of custom tags in my audio files, like instrument types, date of composition or first performance, comment etc., which I rely on a lot in the desktop version of foobar2000. For the mobile version I tried something like this:

[label]
108,2950,2450,100
left
[rgb-135-135-135][comment]

But all it does is display "[comment]", but not the content of the tag. Is there any way to display custom tags at all?